Takafumi Ohnishi
(Fujitsu Limited, Japan)

Hayabusa is a spacecraft to explore the asteroid (25143) Itokawa. It arrived at the target asteroid in September 2005. Hayabusa used an Ion Engines System (IES) as main propulsion in cruising. From the viewpoint of orbit determination, an error in acceleration modeling of ion propulsion has a great influence on orbit determination. It was necessary to navigate the spacecraft accurately by ion propulsion before the end of trajectory transformation on March 2010. Therefore, orbit determination was performed with estimation of ion propulsion direction error. Trajectory Correction Maneuvers (TCM) were accomplished five times by ion propulsion from April to June 2010. Each TCM was performed only by ion propulsion, and Doppler data were monitored to watch the real-time status of TCM accomplishment. The cut-off time of ion propulsion for each TCM was determined by the result of Doppler change. Doppler monitoring was used for capsule separation evaluation too. Because the capsule itself could not communicate with ground stations, we could evaluate the separation only by the change of the mother ship's attitude and velocity caused by the separation. The spacecraft and its capsule re-entered to east side of Woomera Prohibited Area (WPA) in Australia successfully on June 13, 2010.

Kazutaka Nishiyama
(JAXA, Japan)

The cathode-less electron cyclotron resonance ion engines, μ10, have propelled the Hayabusa asteroid explorer for seven years since the launch in May 2003. The spacecraft was focused on demonstrating the technology needed for a sample return from an asteroid, using electric propulsion, optical navigation, material sampling in a zero gravity field, and direct re-entry from a heliocentric orbit. Total duration of powered spaceflight was 25590 hours which provided a delta-V of 2.2 km/s and a total impulse of 1 MN?s, approximately. Degradation trend of the thruster performances has been investigated. It seems that the cause of the degradation is mainly due to decrease of effective microwave power input to the discharge plasma induced by increase of transmission loss of microwave feed system and is not due to increase of gas leakage through accelerator grid apertures enlarged by erosion. Unintentional engine stop events have been summarized and analyzed. Most of them were due to limit check errors of backward microwave powers. Such errors will be decreased by careful monitoring of the trend change of microwave backward power as a function of xenon flow rate in future missions.

Kousuke Kawahara
(ISAS, Japan)

Hayabusa returned to the earth on June 13, 2010, it became the world's first explorer which achieved the round trip with an asteroid. After released from the mother ship, the re-entry capsule landed on the Woomera Prohibited Area in the desert in South Australia. The capsule recovery team of JAXA found the capsule within 1 hour after its landing. Four Direction Finding Systems that were developed by JAXA and a helicopter had very important roles in order to track of the re-entry capsule with a beacon signal. Especially, the Direction Finding System that has high mobility can be built by a few operators within a day and can be used in an environment of desert. In this presentation, we report the beacon tracking system and evaluate the system by discussing results of total-test and re-entry day's operation.

Tetsuya Yamada
(ISAS/JAXA, Japan)

Hayabusa sample return capsule, separated from the mother spacecraft, has entered the earth atmosphere in the desert of the Australia on June 13, 2010, and landed successfully on the ground after passing through the ecessively high aerodynamic heat load with about 15 MW/m2. All the component modules of the SRC have been recovered by June 15. The present paper overviews the reenrty flight of the Hayabusa sample return capsule and post-flight analysis of the recovered heatshields: The post-flight analysis program is planned by 3 steps and is under progress : The first step is reconstruction of the reentry fligh trajectory and the flight environement. The reentry trajectory was reproduced synthetically taking account of the accuracy of the reentry orbit determination, the SRC landing point, atmospheric density and the wind on the reentry day. And the second step is to overview the SRC through non-intusive method such as X-ray CT-scanning. The 3-dimensional laser-scanning has been also carried out for measurering the surface recession. Regardless of difficulty in the surface roughness, emissvity dispersion etc., 3-D surface has been numerically reconstructed and compared with the CAD data at the pre-flight.

Akio Fujimura
(ISAS/JAXA/Graduate University for Advanced Studies, Japan)

Hayabusa's sample capsule was returned at Woomera Prohibited Area of Australia in 13th, June, 2010, and transported to the planetary material curation facility at Sagamihara campus of JAXA, in 18th, June. The sample capsule was surveyed by an X-ray CT method, and the sample container was removed from the capsule. After the verification of several mechanisms in the sample container by a micro X-ray CT method, the sample container was opened in a controlled clean environmental condition of a clean chamber. The sample catcher part, that stores the solid particles collected at the surface of asteroid Itokawa, was removed from the sample container in highly purified nitrogen environment of the clean chamber. Very tiny particles were collected directly from the sample catcher by using the electro-statically controlled manipulator system that was developed for the present purpose. The other sample collection method using Teflon spatula was employed for effective observation of large numbers but very small size of particle samples. SEM and EDX observation shows that the solid rocky particles on the surface of spatula were of Asteroid Itokawa. At present we prolong the preliminary analysis of the Hayabusa's sample for representing the characters of solid particle samples.